This application claims Paris Convention priority of DE 100 37 586.3 filed Aug. 2, 2000 the entire disclosure of which is hereby incorporated by reference
The present invention concerns a canceling device for a blinker switch in motor vehicles which effects automatic canceling of the blinker switch from one of the two switched positions into the neutral central position, comprising a casing with at least one catch profile, and having a movable pretensioned trigger finger which is disposed in the switched positions such that it can be actuated by a cam connected to a steering shaft, and comprising a switching piece which is pivotable and equipped with at least one pretensioned catch element engaging in the catch profile.
A canceling device of this type has been commercially available. When the blinker switch is switched on, the switching piece releases the trigger finger which is caused, due to its pretension, to move radially inward towards the steering shaft and projects into a circular path of the cam connected to the steering shaft. The switching piece is held in the switched position by a pretensioned catch element engaging in a depression of the catch profile.
When, during a corresponding turning motion of the steering wheel, the cam connected to the steering shaft is moved past the trigger finger, the trigger finger is pivoted sidewardly. Carrier surfaces provided on the trigger finger thereby engage a shoulder of the catch element to pull same, in opposition to its direction of pretension, out of the depression in the catch profile. The switching piece together with the blinker switch can thereby snap back into their neutral central positions.
The forces required for actuating the trigger finger in the known canceling device are relatively large. This does not provide a problem for the user turning the steering wheel, who cannot feel this force due to the very favorable lever conditions. The large forces which occur during actuation cause, however, different problems: In many modern vehicles, a steering angle sensor is also disposed in the region of the canceling device which is used for electronic determination of the steering angle. The signals provided by the steering angle sensor are used e.g. by an electronic stabilization device for the vehicle. The reliability of the signals provided by the steering angle sensor is therefore very important. To reduce the amount of space needed and the number of required parts, the canceling device for the blinker switch and the steering angle sensor are often mounted to a common support.
The large forces which occur at the canceling device during its actuation can deform the support to which the canceling device and the steering angle sensor are mounted. These deformations falsify the signals provided by the steering angle sensor.
It is therefore the underlying purpose of the present invention to further develop a canceling device of the above-mentioned type such that the forces produced during actuation of the trigger finger are reduced.
This object is achieved in a canceling device of the above-mentioned type in that the catch profile has at least one movable locking section and the trigger finger is connected to the movable locking section such that the locking section releases the catch element when the trigger finger is actuated.
In accordance with the invention, for automatic canceling of the blinker switch, the catch element is not returned in opposition to the pretensioning force but rather the path which the catch element must follow between the switched position to the neutral central position xe2x80x9cis clearedxe2x80x9d. The forces which are required for moving the locking section are much smaller than those of prior art which were required to move the catch element in opposition to the spring force. In theory, only the frictional force between the locking section and the catch element must be overcome. For this reason, the deformations to which the canceling device and the carrier connected therewith are subjected during actuation from one of the two switched positions into the neutral central position are very small which considerably improves the measuring accuracy of a steering angle sensor disposed on the same carrier.
Advantageous embodiments of the invention are given in the dependent claims.
A locking section which is easy to realize is formed in a further development of the invention on a part which can be pivoted like a door. Alternatively, the locking section can also be formed on a linearly displaceable part.
A deflecting element can preferably be provided to transfer the actuating motion of the trigger finger to the locking section. A deflecting element of this type can convert the direction of motion of the trigger finger in a simple fashion such that the locking section can be moved in any direction required e.g. by installation considerations. In addition, such a deflecting element permits realization of various lever arms for changing forces or stroke lengths.
In a preferred further development of the inventive canceling device, the deflecting element comprises a slot in the region facing the locking section whose longitudinal axis is disposed at an angle with respect to the direction of motion of the locking section, wherein the locking section is connected to a pin which engages the slot. The movement of such a deflecting element can be transformed into a motion of the locking section in a simple fashion.
A further development is particularly preferred wherein the locking section is kinematically locked in its locked position. This type of kinematic locking can be effected without a spring element, the load of which would have to be overcome during motion of the locking section. With such a restoring device, the movement of the locking section into a position in which the catch element is released requires very little force.
An example of such kinematic locking of the locking section is effected when the longitudinal axis of the slot is bent and the longitudinal axis of that region of the slot containing the pin of the locking section in the neutral central position is substantially at right angles with respect to a radius line intersecting the axis of rotation of the deflecting element and that region.
When the blinker switch is in the neutral central position, the locking section is in a position in which the catch element is arrested in its central position. In this neutral central position, the described geometrical arrangement allows the locking section to only transfer forces to the deflecting element whose line of action passes through the axis of rotation of the deflecting element. The corresponding lever arm is equal to zero such that loading of the locking section does not move the deflecting element and the locking section remains locked. Only a motion of the deflecting element moves the pin of the locking section into the other region of the slot in which the mechanism is unlocked.
An alternative to the angled slot is given in a further development, wherein the deflecting element comprises a stepped slot in its section facing the locking section into which a pin, connected to the locking section, engages. Such an embodiment is particularly preferred when the locking section is formed on a linearly displaceable part.
The inventive canceling device can comprise at least one tensioning element which loads the deflecting element into its neutral central position. In connection with a purely kinematic locking of the locking section, the force required for actuating the trigger finger is substantially given by the tensioning force of this tensioning element. Since this can be very small, the required actuating force is also correspondingly small.
The tensioning element can thereby comprise a helical pressure spring whose one end is received in a sleeve having a closed end which is rounded or semi-spherical, wherein the closed end of the sleeve is preferably received in a corresponding depression in the casing. In this further development, the helical pressure spring can be oriented in correspondence with the position of the deflecting element. The depression is thereby preferably also rounded and dimensioned such that a corresponding pivoting motion of the sleeve and simultaneously of the helical pressure spring is possible.
To improve engagement of the tensioning element on the deflecting element, the invention also provides the deflecting element with a pin-like shoulder which the tensioning element surrounds at its free end, or a recess into which the tensioning element engages.
To secure the trigger finger against tilting, the trigger finger can be further provided with at least one supporting wing for support on the deflecting element.
In a further development of the invention, the casing comprises a wall element which is provided with a guiding slot which extends parallel to the longitudinal axis of the trigger finger, into which a guiding pin of the trigger finger engages and/or at least one guiding slot into which a guiding pin engages which is disposed on a section of the deflecting element. Such guiding slots guide the trigger finger and/or the deflecting element to ensure even more accurate motion of the corresponding elements.
The guiding slot can thereby constitute a stop for the path of motion of the trigger finger or of the deflecting lever. Such a stop can e.g. delimit the maximum linear motion of the trigger finger out of the casing. The final positions of the deflecting lever can likewise be defined in a simple fashion.
The forces which are required to move the switching piece from its neutral central position into one of the switched positions, can be reduced if the catch element comprises a rotatable roller on its end facing the catch profile. It is, of course, also possible to provide a ball-shaped or a similar element instead of a roller, which turns along the catch profile, with little friction, during motion of the catch elements. The wear on the catch profile and on the catch element in the region of the contact surfaces is thereby also reduced.
The catch profile can furthermore comprise a canceling section having a step which must be overcome when actuating the catch element into the switched position. Such a step produces a defined engaged position which the user can feel when engaging the blinker switch.
One further development of the invention is particularly preferred, wherein the locking section comprises a rounded and/or flattened locking edge. A locking edge of this type produces a defined contact point between the catch element and the locking section in the switched position of the indicating switch, i.e. when the catch element is locked by the locking section.
In accordance with the invention, the trigger finger can abut a pretensioned intermediate part and have a projection in the contacting area which engages with play behind a recess in the intermediate part. This permits pre-mounting and pre-tensioning of the intermediate part on the trigger finger without having it rotate out of the mounted position in response to pre-tensioning. This considerably simplifies installation of the canceling device.
A further similar development provides that the locking section is connected to a mushroom-like shoulder which engages with play in a corresponding recess in the casing. This mushroom-like shoulder facilitates assembly in that the locking section can be pre-mounted on the casing such that it cannot drop out during assembly of the other parts.
Finally, it is particularly advantageous when the trigger finger comprises a control body having a substantially square overall contour. Such an actuation section permits a maximum path of motion for the loaded part, in particular of a deflecting element with which the control body cooperates.
Two embodiments of the invention are described in detail below with reference to the accompanying drawing.